Donald Trump said the fatal shooting of a young woman at a popular San Francisco tourist spot was further proof the U.S. needs to crack down on border control, his latest in a string of controversial comments about immigration policy.

Kathryn Steinle, 32, was gunned down at Pier 14 in San Francisco on Wednesday. San Francisco Police Chief Greg Suhr told NBC Bay Area that the suspect arrested in the shooting — Francisco Sanchez — had "made an admission" with regards to the seemingly random shooting.

Trump seized on the killing on Friday to tout his immigration views after it emerged that Sanchez is an undocumented immigrant who has been deported from the U.S. five times.

Kathryn Steinle was shot dead at San Francisco’s Pier 14 while out for an evening stroll with her father along the waterfront.Steinle Family

U.S. Immigration and Customs Enforcement said Sanchez was turned over to San Francisco authorities in March, and that the agency had asked for him to remain in custody until immigration authorities could pick him up. That request was not honored, ICE told The Associated Press. Sanchez's criminal history includes seven prior felony convictions, four of which involve narcotics charges, ICE said in a statement.

San Francisco is a "sanctuary city," one of a host of places across the U.S. that gives some protection to illegal immigrants by barring local officials from asking people about their immigration status. Steinle's death has sparked debate over whether sanctuary cities need to re-examine their policies.